Study On The Temperature Induction Mechanism Of The Composite Structure Of Silver Nanoparticles And Upconversion Nanocrystals

Recently,nanothermometers have received widespread attention due to their advantages in the fields of cell temperature measurement,nanodevice temperature monitoring,and biomolecular temperature tracking.In the research of these nano-thermometers,lanthanide-doped upconversion nanoparticles(UCNPs)as nano-scale temperature probes have attracted special attention because of their high-resolution thermal readings,because UCNPs can pass through the intermediate length of lanthanide ions.The conversion between life energy states converts low-energy near-infrared light into high-energy visible light,thereby showing a background-free fluorescent signal for optical temperature measurement.Previous reports have shown that lanthanide Er³⁺ions with thermally coupled energy levels of~2H_11/2and~4S_3/2are one of the best choices for optical temperature sensing,because they have a significant difference in response to temperature changes,which can produce high resolution The temperature gradient and good reproducibility.In addition,because metal nanomaterials have good thermal conductivity and plasma effect,the combination of metal nanomaterials and up-conversion nanoparticles can achieve more effective temperature detection.In this paper,a composite material composed of up-conversion nanoparticles with a core-shell structure and metallic silver is designed and prepared,and the temperature measurement performance and heat conduction efficiency of the composite material in optical temperature detection are studied.The main research contents of this paper are as follows:(1)The classic solvothermal method is used to synthesize core-shell structure upconversion nanoparticles;the sol-gel method uses sodium citrate as a reducing agent to reduce silver nitrate to prepare Ag nanoparticles,and the stobe method uses ethyl orthosilicate as the silicon source.The SiO₂shell is wrapped in an alkaline environment;the Ag@C@Ag core-shell composite is prepared by hydrothermal method using glucose as a carbon source,and its optical properties and structural properties are studied by various characterization methods.(2)Using experimental synthesis of core-shell structured upconversion nanomaterials and Ag@C@Ag nanomaterials to form a composite film,using Al template as a base to study the temperature measurement performance and heat transfer of composite films with different Ag@C@Ag content Sense of efficiency.Experimental analysis of the surface upconversion nanomaterials and Ag@C@Ag materials according to the proportion of composite film can improve the temperature response rate of UCNPs-Ag@C@Ag composites,and it is 264%higher than that of single UCNPs.(3)On the basis of the experimentally synthesized core-shell structured upconversion nanomaterial,the UCNPs shell is wrapped with a SiO₂shell layer,and through electrostatic adsorption,silver nanoparticles are adsorbed on the SiO₂outer layer to achieve upconversion nanoparticles and metal The compound of silver forms a new compound structure.In addition,by controlling the SiO₂shell layer to adjust the coupling distance between the upconversion nanometer and metallic silver,the local field enhancement based on the surface plasmon effect realizes the enhancement of the upconversion luminescence,and the detection of the experimentally constructed composite material in the optical temperature detection Performance and temperature sensitivity.